Duddell, William du Bois

SUBJECT AREA: Electricity

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b. 1872 Kensington, London, England

d. 4 November 1917 London, England

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English engineer, inventor of the first practical oscillograph.

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After an education at the College of Stanislas, Cannes, Duddell served an apprenticeship with Davy Paxman of Colchester. Studying under Ayrton and Mather at the Central Technical College in South Kensington, he found the facilities for experimental work of exceptional value to him and remained there for some years. In 1897 Duddell produced a galvanometer which was sufficiently responsive to display an alternating-current wave-form. This instrument, with a coil carrying a mirror in the air gap of a powerful electromagnet, had a small periodic time. An oscillating mirror driven by a synchronous motor spread out the deflection on a time-scale. This development became the first commercial oscillograph and brought Duddell into prominence as a first-rate designer of special instruments. The Duddell oscillograph remained in use until after the Second World War, examples being used for recording short-circuit tests on high-power switchgear and other rapidly varying or transient phenomena. His next important work was to collaborate with Professor Marchant at Liverpool University to investigate the characteristics of the electric arc. This led to the suggestion that, coupled to a resonant circuit, the electric arc could form a generator of high-frequency currents. This arrangement was later developed by Poulson for wireless telegraphy. Duddell spent the last years of his life on government research as a member of the Admiralty Board of Inventions and Research and also of the Inventions Board of the Ministry of Munitions.

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Principal Honours and Distinctions

CBE 1916. FRS 1907. Royal Society Hughes Medal 1912. President, Institution of Electrical Engineers 1912 and 1913.

Bibliography

1897, Electrician, 39:636–8 (describes his oscillograph). 5 March 1898, British patent no. 5,449 (the oscillograph).

1899, with E.W.Marchant, "Experiments on alternate current arcs by aid of oscillograph", Journal of the Institution of Electrical Engineers 28: 1–107.

Further Reading

V.J.Phillips, 1987, Waveforms, Bristol (a comprehensive account).

1945, "50 years of scientific instrument manufacture", Engineering, 159:461.

GW